This invention relates to a power tool support, and more particularly to a support for taking up the torque reaction arising when operating a manually portable power tool.
During use of for instance a hand held power wrench at an assembly line in a factory an operator has to perform daily a great number of nut or screw tightening operations. At each of such operations the operator has to take up the torque reaction from the wrench by muscle power, which means that he is subjected to rather heavy strains.
With most heavy duty power wrenches of the continuous torque type the output torque and accordingly the reaction torque is too high for an operator to manage. Therefore, such heavy duty power wrenches have been provided with reaction torque arms extending from the wrench housing to the work piece for taking support on the latter.
A reaction torque support of this type has to be of such a shape as to be able to engage a protruding part of the work piece and transfer the reaction torque thereto. Such an arrangement is disadvantageous in that the support arm has to be specifically adapted to the actual work piece or to the screw joint location thereon and might not be suitable for obtaining a proper support at another work piece or at another screw joint on the same work piece. So, support arms of different shapes have to be utilized for different screw joints.
The above described arm type reaction support is disadvantageous also in that its engagement with the work piece might accidentally get lost, for instance by slipping, during the tightening process. At such a loss of support the entire tool suddenly starts rotating backwards and the operator might get hurt.
Another application for a reaction torque in portable drilling machines which due to heavy drilling torque or sudden drill jamming may put too heavy a load on the operator.